Solar power towers are utilized to receive concentrated solar radiation to produce high-temperature thermal energy to generate utility-scale electricity or perform solar chemistry. To generate high thermal energy, solar power towers are located in fields that include numerous heliostats that collect and concentrate solar energy onto a central collector (e.g., solar receiver). For instance, the central collector is oftentimes mounted on top of the solar power tower. A heliostat includes, for example, a plurality of mirrored facets on a common frame that has two axis drives, such that the heliostat can track the sun over the course of a day. Current solar power tower fields include hundreds to thousands of heliostats. Moreover, solar power tower fields can include heliostats located at varying distances from the solar power tower. For example, the farthest heliostats from the solar power tower in some solar power tower fields can be at least a mile away from the solar power tower.
To obtain substantially optimal concentrated solar flux on the central collector from a heliostat, it is desirable for the heliostat to track and aim accurately since a very small error in tracking can result in a reflected solar beam that misses the central collector. Moreover, when a heliostat is positioned at a large distance from the solar power tower, a beam reflected by the heliostat commonly diverges and resulting irradiance on the central collector may be a fraction of one sun. Due to the divergence and low irradiance of the beam at large distances from the heliostat, however, it may be difficult to evaluate the beam from the heliostat.
Traditional approaches for evaluating a beam reflected by a heliostat commonly use a photographic flux image technique. When employing such an approach, incident solar radiation from the sun can be reflected by a heliostat. The heliostat can reflect the beam onto a target, wall, or other type of surface. Further, a camera can capture an image of the beam reflected off of the target, wall, or other type of surface. Moreover, a sensor such as a flux gauge can be employed to scale pixel values from the reflected image captured by the camera. However, as the distance between the heliostat and the target, wall, or other type of surface increases, the irradiance from the beam received at the camera can decrease. Accordingly, as the irradiance decreases, it becomes more difficult to distinguish the beam reflected by the heliostat from ambient light in the reflected image captured by the camera, thereby detrimentally impacting an ability to evaluate the beam reflected by the heliostat.